A method of data compression is known in which, from time-series data that is input, point data constituting the time-series data is subjected to thinning. In regard to such a method of data compression; the Box Car algorithm, the Backward Slope algorithm, and the Swinging Door algorithm are available.
The Swinging Door algorithm is a representative example of the algorithms in which data thinning is achieved by performing linear approximation in such a way that the error is equal to or smaller than a predetermined threshold value. In the Swinging Door algorithm, a single point is fixed as the starting point, and linear approximation is performed in such a way that the error is equal to or smaller than a predetermined threshold value.
There is a trend of an increase in the types and the size of time-series data stored in time-series databases. In that regard, there has been a demand for a method which would enable achieving compression of time-series data in a more efficient manner.